Wireless local area networks are commonly used to provide network connectivity, and one popular protocol for high speed wireless communications is 802.11n MIMO as described in the 802.11 family of Institute of Electrical and Electronics Engineers (IEEE) family of wireless local area network (WLAN) standards. Network adapters which use the MIMO protocol have N multiple antennas, each coupled to an analog front end having a transmit input and a receive output, with the analog front end receive outputs coupled to an N channel MIMO baseband processor, where the MIMO baseband processor generates M spatial streams which are combined in some manner at a MIMO equalizer and data streams are separated and coupled to the input of a media access controller (MAC) which includes a host adapter interface such as PCI coupled to a laptop computer or gateway. In the transmit direction, the MAC has a transmit output which is coupled to a baseband processor which generates N channels of modulated data, each of which is coupled to an analog front end transmit input. In a typical M×N MIMO station (STA), the subject station has N antennas and associated analog front ends, each operative on one of the N spatial streams, and the station extracts M data streams that were transmitted by the M remote antennas at the access point (AP). In the present invention, a spatial stream is associated with each antenna that forms the MIMO channel and optionally individual data streams are carried within each MIMO channel, such that N spatial streams of an N×N MIMO stream can carry M data streams. A special case is a SISO stream, where one spatial stream carries one data stream. In a typical MIMO configuration, the plurality M data streams are combined to form a single high speed data interface at M times the native rate R of each single stream. For example, in a 3 spatial stream MIMO network, with each remote transmitter, channel, and local receiver supporting a 150 Mbps (million bits per second) data stream, the host adapter can be configured to generate a single data stream of 450 Mbpd over the WAN.
In one type of wireless network commonly known as a MIMO wireless local area network (WLAN), a plurality of stations (STA) having MIMO capability are directly accessible to a MIMO access point (AP) which has wired or wireless connectivity to another network, where the AP acts as a gateway to that network. Alternatively, the stations may form a peer-to-peer network where the network traffic is directed from one device to another without passing through the gateway. This type of network with physically adjacent stations is known as a Personal Area Network (PAN). In the context of the present disclosure, a WLAN station is one which operates according to at least one of the 802.11 standards as a BSS (Infrastructure) station, and the PAN station operates according to at least one of the 802.11 standards as a peer station in a peering mode. In a PAN, one device is configured as a group owner and sends timing beacon packets, and the other peering stations synchronize to the group owner beacon and transmit during intervals which follow the group owner beacon. One of the consequences of the close physical placement of peers next to each other in a PAN is a reduced RF transmit power level requirement. A PAN network typically has separation distances between peers on the order of a few meters, compared to a WLAN where the distance from a WLAN STA to WLAN AP is on the order of 30 meters in an indoor setting, and significantly longer in an outdoor setting.
It is desired to provide a network host adapter or access point which can reconfigure existing signal processing functions for a MIMO spatial stream into signal processing functions for one or more independent MIMO spatial wireless streams and optionally one or more SISO data streams.
It is desired to provide a network host adapter or access point which can reconfigure for multiple wireless spatial streams, the host adapter or access point having at least one analog front end processor having gain and power control such that reduced transmit power and receive sensitivity is selected when the analog front end processor is configured for a personal area network.
It is desired to provide a network host adapter or access point which provides a first mode which operates transparently as an 802.11n MIMO adapter carrying N spatial streams, with the network host adapter or access point also having a second mode whereby the existing signal processing bandwidth of the MIMO adapter may be divided between a first set of spatial streams less than N and forming MIMO data streams and a second set of spatial streams which remain, the second set of spatial streams carrying at least one spatial stream configured as SISO or MIMO, and containing at least one of either a SISO stream or a MIMO stream.